This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A366648 #27 Jan 05 2024 00:13:41 %S A366648 3,6,10,14,16,20,32,46,52,64,74,128,178,298,346,502,614,634,1912, %T A366648 60394,92116 %N A366648 Numbers k such that 4^k + 1 is a semiprime. %F A366648 The even terms of A092559 divided by 2. - _Max Alekseyev_, Jan 04 2024 %e A366648 14 is in this sequence because 4^14+1 = 17*15790321 is a semiprime. %Y A366648 Cf. A062394, A001358, A004062, A092559. %K A366648 nonn,more %O A366648 1,1 %A A366648 _Sean A. Irvine_, Oct 16 2023 %E A366648 a(19)-a(21) from _Max Alekseyev_, Jan 04 2024